I have a lot of trouble on the reading and ACT science reasoning sections. I get around a 30 if I complete the whole Reading section on practice tests without any worry for time. With the science reasoning, it's random. I sometimes have enough time to do great or sometimes I miss out on a full experiment or two. On the reading I constantly find myself short of a full passage while still struggling and rushing on other passages. Do you have any tips for staying on time?
Here are some tips for managing your time better on both sections! Follow the links for more details.
Save the conflicting viewpoints passage for last. This part takes most people the longest because there are no visuals, and you usually have to read all of the text. It also tends to break up your concentration if you do it in the middle of the section because it requires a slightly different skill set than the rest of the section.
Keep track of how much time you spend on each part. Try not to spend more than 7 or 8 minutes on a passage (and don't linger on an individual question for longer than a minute and 30 seconds). It sounds like inconsistency in timing is an issue for you, so be more vigilant about monitoring how long you've spend on each passage so you can learn when you need to move forward.
Once again, keep track of time. If you always find that you don't get to at least one passage, you're definitely lingering too long on earlier passages. If you notice that you've been on a passage for more than 8 minutes, move onto the next one. The same goes for individual questions - if you spend more than 45 seconds on a question and you can't figure it out, skip it and come back to it later.
Experiment with different reading strategies, and find one that works best for you. Some people do better reading the questions first and going back to the passage to search for details. Other people prefer to skim the passage first. You may be running out of time because you're reading too closely.
Start with the subject matter that makes you feel most comfortable. If that happens to be the last passage (natural science), so be it. It's better from a time management standpoint to get the passages that are easier for you out of the way first.